How do you answer these questions?

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?

Abag contains 4 red, 7 blue and 5 yellow marbles. event a is defined as drawing a yellow marble on the first draw and event b is defined as drawing a blue marble on the second draw. if two marbles are drawn from the bag, one after the other and not replaced, what is p(b|a) expressed in simplest form? a. 7/16 b. 7/15 c. 14/16 d. 14/15

The tile along the edge of a triangular community pool needs to be replaced? ?